The objective of the proposed grant is to use the hormonal regulation of a metamorphosis-associated protein to study the mechanisms of transcriptional regulation of genes by juvenile hormone (JH) during insect development. In Trichoplusia ni and many other insects JH esterase is strongly and positively regulated by its own hormone, JH. This system is attractive for a study on how this, and perhaps other, sesquiterpenoid hormones act to regulate gene expression of a protein and how the hormone can act to regulate gene expression during development of model insects and medically important invertebrates. The specific aims and procedures of the proposed study are: 1)isolate and sequence cDNA and genomic clone(s) for JH esterases(s) in Trichoplusia ni. 2)define through in vivo transformation of Drosophila or in vitro transfection assays on T. ni cell lines specific sequences which are necessary for hormonal activation of expression of JH esterase. 3)define through gel retardation, DNAase I footprinting and methyl interference specific sequences or regions associated with the JH esterase gene which bind proteins following hormonal activation. 4.initiate purification and characterization of proteins identified as binding, after hormonal activation, to sequences flanking the JH esterase gene. The results of these experiments will be new and original data on the molecular mechanisms of action of JH to stimulate gene expression. The use of a protein which becomes highly expressed during metamorphosis as the model for study assures that the findings will further our understanding of, and ability to disrupt, a fundamental and developmentally critical point of regulation of insect development. The occurrence and importance of JH in a wide range of invertebrate groups ensures that the results will have wide significance and applicability towards invertebrates of medical importance.